Question

a/﻿An incident billiard ball (Ball 1) is rolling on a
frictionless tale with a known inital velocity of v1i. It collides
off-center with an identical ball (Ball 2) that is connected with
an almost perfectly weightless string of known length r pinned
horizontally at point A (see figure for above views of table).
After the collision the final velocity of Ball1 is known to be v1f
at an angle of α above the x-axis. Describe (including a drawing)
what happens to Ball2 and determine its force vector in terms of
knows.